1. Field of the Invention
This invention relates to a means for controlling the deployment of a vehicle air bag cushion, and more particularly, to a diffusion panel mounted inside the air bag cushion near the gas inlet opening for controlling and redirecting the flow of incoming gas from an inflator.
2. Description of the Related Art
An air bag restraint system module typically includes; an open-sided canister that encloses an inflator and at least part of an air bag cushion, said canister having a cover which conceals the module from view. When an air bag module is designed for the driver side of a vehicle, the module is located in the steering wheel behind a cosmetic cover which is an integral part of the steering wheel design. When the air bag module is designed for the passenger side of a vehicle, the container may be located just behind the vehicle dashboard, cosmetic cover, or passenger side instrument panel (hereinafter referred to as "dashboard") and the cover may form an integral part of the vehicle dashboard.
When the vehicle is involved in a collision, a crash signal initiates operation of the inflator to cause the air bag cushion to deploy. The inflator produces an inert gas (e.g., nitrogen or argon) and particulate matter. Filters within the inflator remove most of the particulate matter; however, a small amount of particulate may pass through the filter and enter the air bag cushion. Gas from the inflator is directed under pressure, into the air bag cushion. The air bag continues to inflate until sufficient pressure has developed to rupture the tearseams in the steering wheel cover or dashboard, or to move the hinged cover of the dashboard. The air bag cushion then expands rapidly deploying out of the container and through the opening provided in the steering wheel cover or dashboard and into the occupant compartment of the vehicle. As the air bag cushion is directed into the occupant compartment, it is inflated by the continued flow of gas produced by the inflator. Gas from the inflator normally enters the cushion to produce uniform inflation across the air bag cushion. However, due to certain inflator designs resulting in nonuniform flow of gas across the gas inlet opening, one side of the air bag cushion may fill more quickly than the other. Also, a small amount of particulate matter may be transported into the air bag cushion and may pass out of the air bag cushion into the occupant compartment.
A driver side air bag cushion that does not have any internal or external deployment control mechanism, such as a tether deploys rapidly to fill the space between the steering wheel and the driver's head and upper torso. On the passenger side the air bag cushion, which is absent any deployment control mechanism, is directed to rapidly fill the space between the windshield and the occupant's head and upper torso.
During the early stages of the air bag cushion's deployment, it is desirable to slow the forward movement of the air bag toward the occupant and instead expand the air bag cushion between the steering wheel or dashboard of the vehicle and the occupant's torso in order that the momentum of the moving occupant can be initially absorbed from the occupant's lower torso. After the initial contact the air bag cushion continues to provide protection for a short time to the head and upper body of the occupant during a collision. Also, it is desirable to compensate for nonuniform flow of gas from the inflator in order that the air bag cushion inflate evenly across the cushion. Further, it is desirable to provide a secondary means for filtering out particulate matter present in the gas stream.
Wright Jr., U.S. Pat. No. 3,797,855, discloses a bag within a bag for use as a cushion for an automotive air bag. Wright also discloses a pleat system for the gradual deployment of the air bag cushion to reduce the level of noise generated by the air bag cushion. The inner bag has a number of vent holes to permit communication of gas provided by an inflator from the inner bag to the outer bag. Suzuki et al., U.S. Pat. No. 5,018,762, discloses a driver side air bag with an inclined partition having a number of openings for restricting the flow of generated gas to the upper portion of the air bag thereby increasing gas flow to the lower regions of the air bag. Glance, U.S. Pat. No. 3,614,127, discloses a multi-chamber air bag wherein each chamber is separated from the other chambers except for an orifice which permits communication of gas from one chamber to the next. The size of each orifice varies inversely with the distance of the orifice from the source of pressurized gas. These disclosures do not disclose an efficient means for reducing the forward momentum of the air bag cushion. Further, these disclosures do not disclose a method or apparatus for the secondary filtration of the gas generated by the inflator.